1. Field of the Invention
The present invention generally relates to a lighting apparatus, and more particularly, to a lighting apparatus that guides light emitted from light sources without using a solid light guide to emit planar illuminating light.
2. Description of the Related Art
Conventionally a lighting apparatus such as a hollow side-lit lighting apparatus that emits a planar illuminating light by guiding a light emitted from a light source without using a solid light guide has been known. In a typical hollow side-lit lighting apparatus, light sources such as light emitting diodes (LEDs) are disposed such that they are covered by a frame when seen from an illuminated side. Most of the illuminating light emitted from the light-emitting surface of the lighting apparatus is indirect light reflected on a reflector disposed inside the frame that reflects light emitted from the light sources (see, for example, Japanese Translation of PCT Application No. 2010-528444 and Japanese Laid-open Patent Publication No. 2005-214790).
The hollow side-lit lighting apparatus is more advantageous than a direct-type lighting apparatus that includes light sources immediately behind the light-emitting surface and mainly emits direct light from the light sources through a diffuser, in that, the hollow side-lit lighting apparatus can reduce unevenness in brightness and glare (strong and dazzling light) on the light-emitting surface when seen from the illuminated side.
The conventional hollow side-lit lighting apparatus includes a non-light-emitting surface (hereinafter also referred to as a rim frame) that is a part of the frame covering the light sources when seen from the illuminated side. The non-light-emitting surface reduces the area that can be used as the actual light-emitting surface on the light-emitting side of the lighting apparatus, relative to a whole surface area on the light-emitting side. Some lighting apparatuses need a narrower rim frame for a decorative (design) purpose.